Fixtures of this kind are used in prosthesis surgery, wherein the prosthesis, parts of a prosthesis, or a prosthesis holder is/are anchored in the bone tissue of a person with the aid of one or more such fixtures. The fixtures may be used for different types of prosthesis and are of different sizes, said size depending on the type of prosthesis concerned. However, the fixtures according to the present invention are primarily intended for anchorage in tubular bone and may be used, for instance, in the reconstruction of joints, such as finger joints and hip joints. However, the invention is not restricted to these applications and may be applied to secure artificial limbs or other types of prosthesis to the bone tissue of a patient.
The fixture includes an anchoring portion and an application portion. The anchoring portion is secured in the bone tissue of a patient, by screwing said portion into a hole that has been predrilled in the bone tissue, for instance. The application portion is designed to enable it to be connected to prosthesis in a suitable fashion.
When the fixture anchoring hole is provided in the bone marrow in the longitudinal direction of a bone, the mouth of the hole is likely to be widened outwards due to the internal contour of the bone. Subsequent to having driven the fixture into said hole to the position intended, with the anchoring portion fully screwed into the bone material, the application portion will be located in said widened region, either completely or partially
This results in the formation of a space or clearing between the fixture and the bone material. This is unsuitable both with respect to the stability of the anchorage and the healing process. It is therefore desirable to avoid the occurrence of such a space.
Seen against this background, an object of the present invention is to provide a fixture in which this drawback is eliminated, in other words a fixture in which the occurrence of a space or clearing between the fixture and the bone tissue at the application portion of said fixture is avoided.